THE CRYSTAL-STRUCTURE OF 1-(N(A)-TRIFLUORACETYLALANYL)-INDOLINE

The crystal structure of the title compound, C13H13N2F3O2, (NTFAAI her eafter) has been determined from three-dimensional X-ray diffraction d ata. The structure is monoclinic, C2, with a = 19.023(5), b = 7.574(2) , c = 10.405(2), angstrom, beta = 114.17(2)-degrees, V = 1368(1) angst rom3 and Z = 4. The structure was solved by direct methods and refined by full-matrix least-squares calculations to a final residual of 0.05 1 for 1030 observed reflections [I greater-than-or-equal-to 3sigma(I)] . The molecule comprises an indole ring bound to a trifluoracetyl grou p via an alanine. Both the six- and five-membered rings are coplanar t o a very good approximation, since they form a dihedral angle of 1.6(2 ) degrees. The trifluorocarbon group is tetrahedrally coordinated with the two carbonyl oxygens located on their peptide plane. All bond dis tances and angles demonstrate no significant deviations from standard values.